There is little evidence to suggest a definitive relation between caffeine and weight loss, though it is found in various sources such as coffee, cocoa and other such products.

What is available is plenty of theories that have not been substantiated through research and tests. However, according to many theories because of its appetite suppression properties caffeine may help in reduced intake of food which might have a positive impact on weight reduction.

But such weight reduction can be very temporary to say the least. There is also another theory to state that caffeine causes thermogenesis which is nothing but product heat and energy which helps in burning excess calories. But this again is more of a theory with no scientific claims to back it up. In some cases it has been found that caffeine could act as a good diuretic which may help in increasing the urine output. But since this is essentially fluid loss, weight reduction because of this factor is also very temporary in nature.

Further we have to keep in mind that almost all the tests done to prove the positive effects of caffeine have been of poor quality or have been performed on animals. So it is very difficult to extrapolate these results and apply them on human beings. There is also one theory which states that even decaffeinated coffee can also lead to mild/moderate weight loss. So the premise that caffeine alone causes weight loss is very much under a cloud unless it is proved otherwise.

We have to be careful about the quantity of caffeine that we take because too much of caffeine may cause increased BP, nausea, insomnia, nervousness and various other problems. There are many caffeinated drinks that are rich in fat and calories and overusing them can cause more problems than solutions as far as weight management is concerned. Read also about Liquid Diets for Weight Loss!